1. Field of the Invention
This invention is a circuit for power combining two or more amplifier elements at microwave frequencies employing a novel coupler which simultaneously couples with an arbitrary power coupling (combining or dividing) ratio and matches to an arbitrary impedance.
2. Description of the Prior Art
A prior art search was performed and uncovered the following U.S. patent references:
U.S. Pat. No. 3,772,616 is an impedance matching power divider. The power division ratio is always unity, unlike in the present invention. The patent speaks just in terms of power division, not power combining as in the present invention. The branches of the circuit are rectangular, not curved as in the present invention.
U.S. Pat. No. 3,516,024 is a coupler with no impedance transformation capability, and without the capabilities for an arbitrary power division or combining ratio.
U.S. Pat. No. 3,423,688 shows various couplers but does not show impedance transformation.
U.S. Pat. No. 3,654,570 is a hybrid junction device without having an arbitrary power coupling ratio. In order to fulfill the prophecy of column 3 line 53 et seq. that other impedance values can be accommodated, the patentee would have to use additional components not shown in his patent.
U.S. Pat. No. 4,127,831 is a coupler which does not match impedances other than 50 ohms. The function of the stubs is to broaden the 50 ohm bandwidth.
U.S. Pat. Nos. 4,127,832 and 4,027,254 are couplers without an impedance transformation capability.
Secondary references are U.S. Pat. Nos. 3,237,130, 3,600,707, 4,016,503, and 3,063,026.